Method of finishing articles



y 1942- F. E. DRUMMOND ETAL- 2,283,420

METHOD OF FINISHING ARTICLES Filed July 19, 1939 fiPRnY, DlP,oR FLOW Flmsu (omosmou Puma uuuan Hem Lamps unm new FREE 0R UNTIL THE fimsn 51am: To WNNKLE Ayn DRY oR FoncE Am DRY T0 Paonuce Hana WRlNKLE fmum Inventors Fou om E. DRuMMouo \mu. MR. Wnum; y

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Patented May 19, 1942 METHOD or rmrsnmc. ARTICLES m... a. Drummond and William A. Waldie, Dayton, Ohio, minors to New Wrinkle, 1110., Dayton, Ohio, a corporation of Delaware Application July 19, 1939, Serial No. 285,406

2 Claims.

This invention relates to a method of applying and drying finishes, and more particularly an improved method of producing wrinkle finishes. The invention is also adapted for accelerating the air drying or baking of various types of coating compositions to a hard finish.

It is an object of this invention to provide a method whereby the drying time of coating films and the time required to produce a hard dry finish are substantially shortened by initially subjecting the coating film to radiant heat energy for a limited time before completing the drying of the film to a hard durable finish.

Another object is to provide an improved method of drying coating films to a hard wrinkle finish wherein the wrinkling of the film is initiated prior to the oxidation, curing or setting of the film. I Another object is to provide a process whereby coating compositions such as the conventional oleoresinous varnishes and paints which ordinarily dry to a smooth, non-wrinkle finish, whenapplied and dried as a film, can be made to dry to a wrinkle finish.

Another object is to devise a method of finishing articles with a wrinkle finish comprising ap-' plying a wrinkling enamel or a lacquer thereto and subjecting the coating to concentrated heat ray energy in the near infra-red region.

Another object is to provide an improved method of finishing materials with a wrinkle finish comprising coating the material with a wrinkle finish composition, thereafter subjecting the coating film to infra-red heat rays until the surface of the film begins to wrinkle and then air drying or orce air drying the finish to provide a hard wrinkle finish.

Another object is to devise an improved process of drying coating films comprising subjecting the film to radiant heat energy which will be substantially completely absorbed by the coating film. To accomplish this a radiant heat source is used producing the energy in wave lengths which are readily absorbed by the coating film so that it will dry rapidly to a hard finish.

Another object is to provide an improved process of finishing. articles in a wrinkle finish wherein coating compositions which dry rapidly to a tack-free film are made to wrinkle by the application of infra-red rays thereto as a preliminary step to the final drying of the coating.

Another object is to provide an improved method of drying coating films of both wrinkling and non-wrinkling type wherein costly heating ovens or similar apparatus is substantially eliminated.

These and other objects and. advantages will occur-to those skilled in the art in view of the following description, drawing and appended claims.

General procedure It has been observed where conventional wrinkle finish coating compositions have been altered to produce a coating which will dry tack-free in a relatively short time that in many instances the film fails to develop an irregular or wrinkle surface but dries to a smooth, non-wrinkle film. Where, however, the drying of this type of finish is stimulated by the application of heat rays, particularly of the infra-red or near infra-red radiant energy, wrinkling of the superficial surface of the film is initiated so that the dryin of the film will proceed to produce a wrinkle finish. The essential step in the method of this invention, which has been found to produce the new and unexpected results, is the pre-treatment of the coating film with infra-red rays prior to the subsequent treatment of the film to produce a hard finish.

Generally the improved method comprises the following steps:

Step I The surface of the article to be finished, which has previouly been thoroughly cleaned, is coated with a film of the coating composition desired. Any of the well-known varnish or enamel formulations heretofore applied as a film and dried at elevated temperatures to produce wrinkle finishes may be used, such as disclosed in the patents to Root 1,689,892, 1,864,763, 1,950,417, 1,976,191, and Phillippi 1,878,316 and 1,936,913. The coating may be applied in any suitable manner such as by spraying, dipping, flowing or brushing the composition on the article.

Step II Following the application of the coating composition the article is placed under a heat lamp or suitable infra-red radiating means for from five to fifteen minutes or, in the case of wrinkle finishes, until the wrinkling of the surface is initiated; thereafter the treatment is terminated.

Step III The pre-infra-red rays treated finish is then allowed to air dry or is alternatively force air dried at from 85' to 250 degrees F. to produce a 55 hard durable smooth or wrinkle finish.

Finishing method and apparatus In the drawing there is illustrated a method and apparatus for finishing articles to provide a wrinkle finish therefor in which:

Figure 1 shows in perspective an arrangement comprising a device whereby the article being finished may be sprayed with a coating composition. subjected to radiant heat energy and force air dried or baked while said article is conveyed along on an endless belt means;

Figure 2 illustrates graphically and diagrammatically the steps of the improved process of this invention comprising applying and drying coating compositions to provide a hard wrinkle finish.

Referring to the drawing in detail, the reference numeral iii-is used to indicate the article being finished which may be made of any suitable material and of any desired shape. For conveying the articlealong there may be provided an endless belt conveyor II or similar means. as shown in Figure 1. It will be understood that prior to applying the coating composition by a spray means I! the surface of the article has been thoroughly cleaned.

After application of the coating the article is moved or placed under the heat lamps i3 where the film is subjected to concentrated infra-red heat rays. For this purpose any suitable source of infra-red radiation may be used. Preferably a carbon filament lamp of 250 to 300 watt capacity is employed; however, strip or wire metal heaters or even radiation from the sun may be utilized. Radiant energy of a wave length, between 7200 to 14,000 A. (Angstrom units), referred to as the near infra-red radiation portion of a spectrum, is preferred since generally the coating compositions used have the greatest absorption in this region of the spectrum and accordingly wave lengths in this region are the most effective for stimulating the drying and wrinkling of the film. I

This preliminary infra-red ray treatment of the coating is to be distinguished from the subsequent baking or force air drying of the finish wherein the. conventionally heated baking ovens are used. In the latter'instance the heat rays are of wave lengths above 14,000 A. which are generally not suited for initiating wrinkling of the coating film.

When the coating has been exposed to the radiant energy of the heat lamps I! for sufiicient time to bring about initiation of wrinkles in the finish, which generally is effected within five to fifteen minutes, the coated article i is then moved into the drying oven I where it is subjected to heated air at a temperature ranging from 85 to 250 degrees F., depending upon the particular type of coating composition used, until a hard tough finish is produced. The oven I4 is suitably equipped with a heating element [5 and exhaust fan means i6 for moving heated air in contact with the article to effectively dry and cure the coating to provide a durable finish. In. Figure 2 the wrinkle finishing of a panel or article designated I8 by the method of this invention is shown. In this instance one or more of the articles which have been previously cleaned are sprayed. dipped or flow coated as illustrated in perspective in Step I of Figure 2. Subsequently the coated article is exposed to heat lamps It, as illustrated in Step II of Figure 2. until the finish begins to wrinkle as indicated at l8, after which the article may be placed aside and allowed to air dry, or if desired force air dried to provide a wrinkle finish 20. Further, completion of the drying may be accomplished by the use of infra-red sun lamps, as in Step II, to produce a hard wrinkle finish.

By initially treating the coating with infrared radiant energy prior to completing the drying it has been found unexpectedly that the time required for producing a hard substantially scratchproof finish is materially reduced as compared with that required'when baking or air drying the coating in the conventional manner. Moreover, a perceptibly harder coating is obtained at lower drying temperature than when the coated article is dried or baked at the required temperature in the usual way. Aside from these improved results and advantages attained by utilizing the process of this invention, the use of expensive drying ovens and relatively high temperature baking treatment for finishing articles is eliminated.

It will be understood that this invention is not limited to thk specific apparatus and method disclosed but ma y be varied to suit different conditions and uses without departing from the spirit of this invention.

Having thus fully described our'invention, what we claim as new and desire to secure by Letters Patent is: I

1. A 2-stage method of drying coating films to a hard wrinkle finish comprising in the first stage the steps of thoroughly cleaning the surface of an article to be finished, applying thereon a coating composition containing wrinkle drying oil as a film forming constituent, and subjecting the coating film to infra-red radiation of between 7200 and 14,000 Angstrom units for a period of 5 to 15 minutes to initiate wrinkling of the film surface; and in .the second stage the step of drying the coating film by infra-red radiation of over 14,000 Angstrom units to complete the polymerization and oxidation of the film to a hard wrinkle finish.

2. A 2-stage method of drying coating films to a hard wrinkle finish comprising in the first stage the steps of thoroughly cleaning the surface of an article to be finished, applying thereon a coating composition containing wrinkle drying oil as a,film forming constituent, and subjecting the coating film to infra-red radiation of between 7200 and 14,000 Angstrom units for a period of 5 to 15 minutes to initiate wrinkling of the film surface; and in the second stage the step of drying the coating film by infra-red radiation of over ,000 Angstrom units in a current of air to set the film to a hard wrinkle finish.

FOLSOM E. DRUMMOND. WILLIAM A. WALDIE. 

